Because it sucks.
This DVD is interesting mainly as an FAQ: Did anyone attend Incantation shows? No. How did they dress? Always the same. Did they move around a lot while playing? No. Do the band members ever even look at each other? No.
Incantation's first two studio albums both suffer from cavernous, obscure recordings, so in theory a live performance would cut through any questions of sound quality, and capture the songs in their intensity and as-executed: there is always something artificial about death metal albums. And these 3 performances do all that, to some degree--but with the qualification that the videos here are essentially unwatchable and also unlistenable. They are all single-source VHS recordings, so the sound is very scrunched together, blown-out, and far from the impact any death metal band aims for in a performance. The best is the "Flashes" show, which is shot from a higher vantage point, and the guitar and drums can be discerned reasonably well (vocals muffled).
But, complain about this as I may, it really isn't about the sound quality or the performance style. At heart, I don't think I like or understand Incantation. I don't "get" it. Are they too cerebral? I hate to admit it, but this might be the case. They don't make it easy for me: lots of changes, atonal solos, few choruses, more "doomy" parts than breakdowns, completely unpleasant but generic vocals. Like Obituary, Incantation seem to have missed out on the original intensity of metal: the quality of up-tempo rock that Metallica have in common with the MC5. Incantation never "rock," no matter how fast they play.
If you want to see a few really ugly guys standing on a stage making barely audible, complicated, uncatchy music that makes Deicide seem extremely charming-- this is for you.